Could an AI be sentient?
In theory, if one could build a computing device that matched or exceeded the cognitive capabilities of a sentient being, it should be possible. 

(Singlarity adherents believe we will one day be able to transfer the human mind into an artificial computing platform, and it logically follows that one could "hack" such a mind, or build from the ground up, to create a truly Artificial Intelligence.)

But this may be like fusion power, where the old adage is that it is "always 20 years away."